DOCSLIB.ORG

A Lithogeochemical Study of the Metal Contents of the Upper Cretaceous Oil Shales in the Pasquia Hills, East-Central Saskatchewan

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A Lithogeochemical Study of the Metal Contents of the Upper Cretaceous Oil Shales in the Pasquia Hills, East-Central Saskatchewan A Lithogeochemical Study of the Metal Contents of the Upper Cretaceous Oil Shales in the Pasquia Hills, East-Central Saskatchewan Murray C. Rogers 1 Information from this publication may be used if credit is given. It is recommended that reference to this publication be made in the following form: Rogers, M.C. (2016): A lithogeochemical study of the metal contents of the Upper Cretaceous oil shales in the Pasquia Hills, east-central Saskatchewan; in Summary of Investigations 2016, Volume 2, Saskatchewan Geological Survey, Saskatchewan Ministry of the Economy, Miscellaneous Report 2016-4.2, Paper A-1, 17p. This paper is associated with the following publication: Rogers, M.C. (2016): Geochemical analyses of drillhole core from Cretaceous Upper Colorado Group oil shale in east-central Saskatchewan (NTS 63E/03, /04); Saskatchewan Ministry of the Economy, Saskatchewan Geological Survey, Data File 41. Abstract The results of a multi-element geochemical study are reported from the selective sampling of core from five drillholes that intersected Cretaceous oil shales on the northwest flank of the Pasquia Hills in east-central Saskatchewan. Black shales, particularly organic-rich shales, commonly have anomalous—and in some cases potentially economic—metal contents. Upper Cretaceous oil shales of the Niobrara (First White Speckled Shale) and Favel (Second White Specks) formations occur at shallow depth, in subcrop and as local outcrop, in the Pasquia Hills, and extend in subcrop and at depth through central Saskatchewan. Although the oil shales in the Pasquia Hills have been extensively drilled and tested for their kerogen (oil) potential since the 1960s, there is no public record that they have been examined in any detail for their metal contents. The core from several recent drillholes from this region is stored in Regina at the Subsurface Geological Laboratory of the Ministry of the Economy. Five of these holes from the northwest flank of the Pasquia Hills were selected for sampling. The oil shale sections in these holes average about 30 m in thickness. Four representative one-metre chip samples of the core were taken from each hole, approximately equidistant through each core section. The samples were then sent for multi-element analysis by inductively coupled plasma–optical emission spectroscopy (ICP-OES) and fire assay (Au, Pt, Pd)–ICP-OES. The United States Geological Survey’s (USGS) standard for metalliferous black shales was used as a basis to interpret the results of the multi-element analyses. The gold values (with one exception) are highly anomalous, with 19 of the 20 samples exceeding the USGS standard of 5.6 ppb. The arithmetic mean (average) value for all 20 samples was 45 ppb (eight times (8X) greater than the USGS standard) and the high value was 129 ppb (23X). Based on the albeit limited number of drillholes and samples, the mean gold values display a general westward increase, with the highest mean value of 103 ppb Au in the most western drillhole. A hydrothermal source to the west is inferred for the anomalous gold. Other metalliferous elements include Ag, Zn, Se, P2O5, Sr and V. Based on the clearly anomalous but unspectacular level of values and the consistent distribution of these metals both within the individual drillholes and between the drillholes, their source has been attributed to absorption of metals by organic matter from seawater and further concentration in minerals during diagenesis in the reduced, anoxic sediments. Keywords: oil shale, Upper Cretaceous, metals, geochemistry, gold, Pasquia Hills, east-central Saskatchewan 1. Introduction The purpose of this lithogeochemical study was to determine the metal contents of the Upper Cretaceous oil shales on a portion of the northwest flank of the Pasquia Hills area of east-central Saskatchewan (Figure 1). Macauley (1984) defines oil shale as an organic-rich, fine-grained, dark brown to black sedimentary rock that contains kerogen from which liquid hydrocarbons can be extracted by heating. Black shales, particularly organic-rich shales, often have anomalous, and in some cases potentially economic, metal contents. 1 Saskatchewan Ministry of the Economy, Saskatchewan Geological Survey, 1000-2103 11th Avenue, Regina, SK S4P 3Z8 Although the Saskatchewan Ministry of the Economy has exercised all reasonable care in the compilation, interpretation and production of this product, it is not possible to ensure total accuracy, and all persons who rely on the information contained herein do so at their own risk. The Saskatchewan Ministry of the Economy and the Government of Saskatchewan do not accept liability for any errors, omissions or inaccuracies that may be included in, or derived from, this product. Saskatchewan Geological Survey 1 Summary of Investigations 2016, Volume 2 Figure 1 – Location of the project area on the northwest flank of the Pasquia Hills, east-central Saskatchewan (geological and urban municipality base map is from the Geological Atlas of Saskatchewan, Saskatchewan Ministry of the Economy website) showing the regional subcrop of the oil shale formations (Kws) and estimated projection of the Tabbernor Fault Zone (TFZ). The Pasquia Hills form the northwestern extent of the Manitoba Escarpment. The area to the east of the town of Arborfield (Figure 2) was selected for this study because the oil shales are near the surface here and, since the 1960s, have been the focus of a number of drill programs because of their kerogen content. The core from several drillholes from recent programs is available for examination and study at the Saskatchewan Ministry of the Economy’s Subsurface Geological Laboratory (SGL) in Regina. Five of these drillholes (Figure 2) from a Questerre Energy Corporation (Questerre) drill program on the northwest flank of the Pasquia Hills in 2012 were selected for core sampling and multi-element analysis. The oil shales in this area, which generally contain ≥5% total organic carbon (TOC), have average cored sections of about 30 m. Figure 2 – Locations of the five Questerre Arborfield drillholes selected for the core sampling program, with the local interpreted geology noted (base map is from the Geological Atlas of Saskatchewan, Saskatchewan Ministry of the Economy website). Locations of other drillholes with core available at the SGL are also indicated (green dots) but not labelled. The complete geochemical results, as well as information on the drillhole and sample locations, are tabulated in Data File 41, a separate publication associated with this paper. Saskatchewan Geological Survey 2 Summary of Investigations 2016, Volume 2 2. Deposit Model for Metalliferous Black Shales Pyritic black shales occur throughout the world and are potential sources of a wide variety of metals that may include Ni, Mo, As, Zn, Pb, Cu, Cd, Co, Cr, U, V, Se, Ag, Au, platinum group elements (PGE), rare metals, and rare earth elements (REE)+(Y,Sc) in addition to oil and industrial minerals. They typically have high organic carbon contents, to which the metal contents are commonly correlated. The stratabound to stratiform mineralization tends to be very large, low grade and regionally extensive, but with rare, notable high-grade exceptions such as in southern China. The black shales are commonly related to periods of widespread oceanic anoxia. Deposits and districts that have been and are being mined include Talvivaara, Finland; Yangtze Platform, southern China; and the Alum Shale, Sweden. There are two principal genetic theories for their formation: 1) hydrothermal metal exhalation along basin margin faults with the deposition of metals in reduced, anoxic sediments; and 2) absorption of metals from seawater onto organic matter, followed by concentration in sulphides and other minerals in anoxic sediments during diagenesis under euxinic conditions. a) World Examples The Talvivaara Ni-Cu-Zn deposit in Finland is a Precambrian example of mineralized, metamorphosed, sulphidic black shale (Loukola-Ruskeeniemi and Heino, 1996). It is hosted by the Paleoproterozoic Kainuu schist belt, which consists mainly of metasedimentary rocks with discontinuous serpentinites. The orebody, which is mined by open pit and bio-heap-leach methods, contains 300 million tonnes grading 0.26% Ni, 0.14% Cu and 0.53% Zn, with 100 ppm Mo, 630 ppm V and 7% organic C. The deposit is up to 330 m thick, although this has been modified by tectonic thickening. Dominant sulphides, comprising pyrrhotite and pyrite with minor chalcopyrite, sphalerite, alabandite and pentlandite, occur as fine disseminations, and as coarser grains in quartz-sulphide veins. Loukola-Ruskeeniemi and Heino (1996) attribute the mineralization to hydrothermal activity in a rift environment with deposition in organic-rich anoxic sediments. Early Cambrian, black shale–hosted Mo-Ni and V mineralization of the Yangtze Platform, China occurs as a thin (a few centimetres) sulphide horizon with a strike length of about 1600 km (Lehmann et al., 2016). Mining occurs intermittently along this extent. The mineralization consists of Mo (~4%) and Ni (~2%), with about 600 ppm V and highly anomalous Zn, As, Se, Au, Ag, PGE and U. Metal enrichment is attributed to an environment of high biological activity, a very low clastic sediment accumulation rate, and a low rate of organic matter deposition in a stratified oxic- suboxic-euxinic basin, with the bottom water/sediment interface scavenging metals under euxinic conditions. The Alum Shale in Sweden has been mined periodically for centuries for alum [KAl(SO4)2-12H2O], oil and uranium (Large, 2012). It is a Cambrian to Lower Ordovician, organic-rich, pyritic shale unit that is 20 to 60 m thick, within black shales that are over 200 m thick. At the Viken project, an NI 43-101–compliant Inferred Mineral Resource of 3.019 billion tonnes grading 172 ppm U3O8, 335 ppm Ni, 120 ppm Cu and 421 ppm Zn has been defined (Continental Precious Minerals Inc., 2014). The deposit was also reported to contain significant concentrations of molybdenum and vanadium. The Nick property in Yukon bears similarities to the southern China deposits (Hulbert et al., 1992).
Load more

Recommended publications
  • Dust, Volcanic Ash, and the Evolution of the South Pacific Gyre Through the Cenozoic
    Dust, volcanic ash, and the evolution of the South Pacific Gyre through the Cenozoic Dunlea, A. G., Murray, R. W., Sauvage, J., Spivack, A. J., Harris, R. N., & D'Hondt, S. (2015). Dust, volcanic ash, and the evolution of the South Pacific Gyre through the Cenozoic. Paleoceanography, 30(8), 1078-1099. doi:10.1002/2015PA002829 10.1002/2015PA002829 John Wiley & Sons, Inc. Version of Record http://cdss.library.oregonstate.edu/sa-termsofuse PUBLICATIONS Paleoceanography RESEARCH ARTICLE Dust, volcanic ash, and the evolution of the South 10.1002/2015PA002829 Pacific Gyre through the Cenozoic Key Points: Ann G. Dunlea1, Richard W. Murray1, Justine Sauvage2, Arthur J. Spivack2, Robert N. Harris3, • Forty-seven element concentrations ’ 2 in 206 bulk sediment samples from and Steven D Hondt fi seven sites in the South Paci c 1 2 • Multivariate statistical models quantify Department of Earth and Environment, Boston University, Boston, Massachusetts, USA, Graduate School of 3 dust, ash, and other fluxes 100–0Ma Oceanography, University of Rhode Island, Narragansett, Rhode Island, USA, College of Earth, Ocean, and Atmospheric • Dust and ash records climate and Sciences, Oregon State University, Corvallis, Oregon, USA meridional shifts in atmospheric circulation Abstract We examine the 0–100 Ma paleoceanographic record retained in pelagic clay from the South Supporting Information: Pacific Gyre (SPG) by analyzing 47 major, trace, and rare earth elements in bulk sediment in 206 samples • Readme from seven sites drilled during Integrated Ocean Drilling Program Expedition 329. We use multivariate statistical • Figure S1 • Table S1 analyses (Q-mode factor analysis and multiple linear regression) of the geochemical data to construct a model • Table S2 of bulk pelagic clay composition and mass accumulation rates (MAR) of six end-members, (post-Archean • Table S3 average Australian shale, rhyolite, basalt, Fe-Mn-oxyhydroxides, apatite, and excess Si).
    [Show full text]
  • September 24-25, 2004 FORWARD
    Flow and Transport: Characterization and Modeling from Pore to Reservoir Scales C=0.2 C=0.4 Figure from Robert Glass Gaithersburg Marriott Washingtonian Center Gaithersburg, MD September 24-25, 2004 FORWARD “Flow and Transport: Characterization and Modeling from Pore to Reservoir Scales” is the eleventh in a series of Geosciences Research Program Symposia dating from 1995. These symposia are topically focused meetings for principal investigators in the program and provide opportunities for our investigators to give presentations to one another and to discuss their Office of Basic Energy Sciences’ supported research. In addition to the recognition the symposium gives to all of the investigators, we traditionally also recognize one outstanding contribution from a DOE Laboratory Project and one from a University Project. The outstanding contributions are selected by our session chairpersons. We are fortunate to have as guest session co-chairs Professor Roger Beckie from the University of British Columbia, Professor Ronald Falta from Clemson University, Professor Mario Ioannidis from the University of Waterloo, and Dr. Michael J. King from BP. They join our Principal Investigator co-chairs Professor Katherine McCall of the University of Nevada, Professor Amos Nur of Stanford University, Dr. Karsten Pruess of the Lawrence Berkeley National Laboratory, Dr. Wenlu Zhu of the Woods Hole Oceanographic Institution. For their efforts on behalf of the investigators I thank them all. We are looking forward to an outstanding series of presentations. Nicholas B. Woodward Geosciences Research Program Office of Basic Energy Sciences U.S. Department of Energy * * * * * Table of Contents Agenda…………………………………………………………………………………… 3 Abstracts (listed in chronological order) Session 1 (September 24, A.M.)………………….……………………………… 7 Session 2 (September 24, P.M.).………………………………………………… 16 Session 3 (September 25, A.M.)…………………...............................................
    [Show full text]
  • 1. Cenozoic and Mesozoic Sediments from the Pigafetta Basin, Leg
    Larson, R. L., Lancelot, Y., et al., 1992 Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 129 1. CENOZOIC AND MESOZOIC SEDIMENTS FROM THE PIGAFETTA BASIN, LEG 129, SITES 800 AND 801: MINERALOGICAL AND GEOCHEMICAL TRENDS OF THE DEPOSITS OVERLYING THE OLDEST OCEANIC CRUST1 Anne Marie Karpoff2 ABSTRACT Sites 800 and 801 in the Pigafetta Basin allow the sedimentary history over the oldest remaining Pacific oceanic crust to be established. Six major deposition stages and events are defined by the main lithologic units from both sites. Mineralogical and chemical investigations were run on a large set of samples from these units. The data enable the evolution of the sediments and their depositional environments to be characterized in relation to the paleolatitudinal motion of the sites. The upper part of the basaltic crust at Site 801 displays a complex hydrothermal and alteration evolution expressed particularly by an ochre siliceous deposit comparable to that found in the Cyprus ophiolite. The oldest sedimentary cover at Site 801 was formed during the Callovian-Bathonian (stage 1) with red basal siliceous and metalliferous sediments similar to those found in supraophiolite sequences, and formed near an active ridge axis in an open ocean. Biosiliceous sedimentation prevailed throughout the Oxfordian to Campanian, with rare incursions of calcareous input during the middle Cretaceous (stages 2, 4, and 5). The biosiliceous sedimentation was drastically interrupted during the Aptian-Albian by thick volcaniclastic turbidite deposits (stage 3). The volcanogenic phases are pervasively altered and the successive secondary mineral parageneses (with smectites, celadonite, clinoptilolite, phillipsite, analcime, calcite, and quartz) define a "mineral stratigraphy" within these deposits.
    [Show full text]
  • Reservoir Quality Study of Siliciclastic and Carbonate
    RESERVOIR QUALITY STUDY OF SILICICLASTIC AND CARBONATE ROCKS 3 days course in Oybin, Germany 12th - 14th of December 2018 Course Agenda 12th - 14th of December 2018 in Oybin, Germany The technical workshop (3 days oral & practical sessions) are aimed at giving specialists from the oil industry a detailed introduction to the study of siliciclastic & carbonate reservoirs. Workshops are structured in oral and practical sessions, with PPt presentations, didactic material/exercises and work at a polarising microscope. Examples of SEM and CL analyses are also shown to integrate the different methodologies utilized for diagenetic/reservoir quality studies. Examples from oil reservoirs from different basins in the world are also taken into consideration. RESERVOIR QUALITY STUDY OF SILICICLASTIC RESERVOIRS MODULE 1: Introduction. Siliciclastic rocks, classification of sedimentary rocks, type of petro-facies, sediment texture (sorting, grain size, grain shape, grain contacts, textural and mineralogical maturity), detrital components. Sandstone classification, ternary plots (Pettijohn, 1987), Optical properties of most important minerals of siliciclastic rocks under PPL and XPL (e.g. undulatory quartz) and their link with source areas (plutonic & metamorphic sources), depositional markers, chemical & mechanical stability of minerals Sandstone composition, provenance and tectonic settings: Data collection methods (Gazzi- Dickinson), litho-types vs. provenance (Dickinson plots), QFL of sedimentary rocks in different tectonic regimes and rock composition vs. porosity/burial depth. Other techniques for provenance studies (CL, Qemscan and geochemistry) will also be explained. Types of depositional environments, Provenance and reservoir quality. Examples from current East & West Africa reservoirs (e.g. Central Atlantic margins). Exercises. MODULE 2: Definition of matrix, pseudomatrix & authigenic components (main cements and replacement components): Compaction, silica cementation, carbonate cementation, feldspar authigenesis, clay minerals and zeolite authigenesis.
    [Show full text]
  • 60° Geological and Petrophysical Parameters of a Deep Fractured Sandstone Formation As Applied to Geothermal Exploitation
    60° Geological and petrophysical parameters of a deep fractured sandstone formation as applied to geothermal exploitation EPS-1 borehole, Soultz-sous-Forets, France *J.F. Vernoux, *A. Genter, *P. Razin, **C. Vinchon december 1995 Rapport du BRGM R 38622 *BRGM, Orléans **BRGM, Nord-Pas de Calais BRGM DIRECTION DE LA RECHERCHE Département Hydrologie, Géochimie et Transferts BP 6009 - 45060 ORLEANS CEDEX 2 - France - Tél.: (33) 38 64 34 34 Mots clés : Geothermal exploitation, Argillaceous sandstone, Sedimentological processes, Diagenesis, Fracture network, Reservoir, Porosity, Permeability, Soultz-sous-Forêts borehole, Rhinegraben, France En bibliographie, ce rapport sera cité de la façon suivante : VERNOUX J.F., GENTER A., RAZIN P., VINCHON C. (1995) - Geological and petrophysical parameters of a deep fractured sandstone formation as applied to geothermal exploitation, EPS-1 borehole, Soultz-sous- Forêts, France, Rapport BRGM R 38622, 70 p., 24 fig., 5 tabl., 3 append. © BRGM, 1995, ce document ne peut être reproduit en totalité ou en partie sans l'autorisation expresse du BRGM. Geological and petrophysical parameters of a deep fractured sandstone formation ABSTRACT In the framework of a European research project dealing with the improvement of the injectivity index of argillaceous sandstone, a basic study of a potential geothermal clastic aquifer was carried out from an exhaustive analysis of deep well data. A core from the base of Mesozoic cover rocks intersected in borehole EPS-1 (Soults-sous-Forêts, Rhine Graben, France) provided a continuous section of the Buntsandstein sandstones (1009-1417m), considered as a potential geothermal reservoir. More than 400 m length of continuous core sections were analyzed in details in terms of sedimentological features, diagenetic evolution, pre-existing fracturation and petrophysical properties in order to define the best potential reservoirs within this deep clastic formation.
    [Show full text]
  • The Gulf of Maine Rutile Province Accumulation of Fine-Grained, Authigenic Titanium Oxide from Sandstone and Shale Source Rocks
    DEPARTMENT OF INTERIOR U. S. GEOLOGICAL SURVEY The Gulf of Maine Rutile Province Accumulation of Fine-grained, Authigenic Titanium Oxide from Sandstone and Shale Source Rocks by Page C. Valentine and Judith A. Commeau Open-File Report 89-532 This report is preliminary and has not been reviewed for conformity with U. S, Geological Survey editorial standards and stratigraphic nomenclature. Hfoods Hole, MA 1989 CONTENTS Page Abstract................................................................. 1 Introduction............................................................. 2 Methods.................................................................. 2 Geologic setting of the Gulf of Maine.................................... 3 Description and source of basin sediment................................. 4 Texture and color..................................................... 4 Composition........................................................... 5 Water content and bulk density........................................ 5 Sediment sources...................................................... 6 Economic aspects of Gulf of Maine TiC^ ................................... 7 Amount of TiO ^ in basin deposits...................................... 7 TiC-2 resources: U. S. and worldwide.................................. 7 Beneficiation of TiO 2 ore............................................. 8 Origin and provenance of fine-grained TiO2............................... 8 Authigenesis of fine-grained TiO *L > .................................... 8 Origin of coarse-grained
    [Show full text]
  • Diagenetic Alteration of Biogenic Opal and Authigenesis of Silica and Silicates1
    9. SILICEOUS SEDIMENTS FROM THE NAURU BASIN: DIAGENETIC ALTERATION OF BIOGENIC OPAL AND AUTHIGENESIS OF SILICA AND SILICATES1 Volkher Riech, Bundesanstalt für Geowissenschaften und Rohstoffe, D 3000 Hannover 51, Federal Republic of Germany ABSTRACT This study deals with the mineralogical variability of siliceous and zeolitic sediments, porcellanites, and cherts at small intervals in the continuously cored sequence of Deep Sea Drilling Project Site 462. Skeletal opal is preserved down to a maximum burial depth of 390 meters (middle Eocene). Below this level, the tests are totally dissolved or replaced and filled by opal-CT, quartz, clinoptilolite, and calcite. Etching of opaline tests does not increase continously with deeper burial. Opal solution accompanied by a conspicuous formation of authigenic clinoptilolite has a local maximum in Core 16 (150 m). A causal relationship with the lower Miocene hiatus at this level is highly probable. Oligocene to Cenomanian sediments represent an intermediate stage of silica diagenesis: the opal-CT/quartz ratios of the silicified rocks are frequently greater than 1, and quartz filling pores or replacing foraminifer tests is more widespread than quartz which converted from an opal-CT precursor. As at other sites, there is a marked discontinuity of the transitions from biogenic opal via opal-CT to quartz with in- creasing depth of burial. Layers with unaltered opal-A alternate with porcellanite beds; the intensity of the opal-CT-to- quartz transformation changes very rapidly from horizon to horizon and obviously is not correlated with lithologic parameters. The silica for authigenic clinoptilolite was derived from biogenic opal and decaying volcanic components.
    [Show full text]
  • Quantifying Early Marine Diagenesis in Shallow-Water Carbonate Sediments
    Available online at www.sciencedirect.com ScienceDirect Geochimica et Cosmochimica Acta xxx (2018) xxx–xxx www.elsevier.com/locate/gca Quantifying early marine diagenesis in shallow-water carbonate sediments Anne-Sofie C. Ahm a,⇑, Christian J. Bjerrum b, Clara L. Bla¨ttler a, Peter K. Swart c, John A. Higgins a a Princeton University, Department of Geosciences, Guyot Hall, Princeton, NJ 08544, United States b University of Copenhagen, Nordic Center for Earth Evolution, Department of Geoscience and Natural Resource Management, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark c Department of Marine Geosciences, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, United States Received 4 August 2017; accepted in revised form 23 February 2018; available online xxxx Abstract Shallow-water carbonate sediments constitute one of the most abundant and widely used archives of Earth’s surface evo- lution. One of the main limitations of this archive is the susceptibility of the chemistry of carbonate sediments to post- depositional diagenesis. Here, we develop a numerical model of marine carbonate diagenesis that tracks the elemental and isotopic composition of calcium, magnesium, carbon, oxygen, and strontium, during dissolution of primary carbonates and re-precipitation of secondary carbonate minerals. The model is ground-truthed using measurements of geochemical prox- ies from sites on and adjacent to the Bahamas platform (Higgins et al., 2018) and authigenic carbonates in the organic-rich deep marine Monterey Formation (Bla¨ttler et al., 2015). Observations from these disparate sedimentological and diagenetic settings show broad covariation between bulk sediment calcium and magnesium isotopes that can be explained by varying the extent to which sediments undergo diagenesis in seawater-buffered or sediment-buffered conditions.
    [Show full text]
  • ABSTRACT Title of Dissertation: AUTHIGENESIS
    ABSTRACT Title of Dissertation: AUTHIGENESIS, BIOMINERALIZATION, AND CARBON-SULFUR CYCLING IN THE EDIACARAN OCEAN Huan Cui Doctor of Philosophy, 2015 Dissertation directed by: Dr. Alan J. Kaufman Department of Geology Fossil record of the Ediacaran Period (635-541 Ma) reveals unprecedented rise of early animal life (metazoan) in Earth history. Coupled with this evolutionary milestone, the Earth’s atmosphere and hydrosphere experienced dramatic redox fluctuations. In order to better constrain the redox architecture of the Ediacaran ocean margin, an integrated chemostratigraphic correlation of the Doushantuo Formation in basin scale was conducted (see Chapter 2). The revised redox model suggests that euxinic conditions on the platforms were mainly restricted in lagoonal settings, which helps us to better understand Ediacaran fossil distributions and fluctuated δ13C records in the Ediacaran strata in South China. One of the most distinct features of the Ediacaran chemostratigraphy is the δ13C negative excursion (i.e. Shuram Excursion, or SE) reported globally, which is the largest known C cycle anomaly in Earth history. In order to understand the biogeochemical processes that gave rise to the SE expressed in the upper Doushantuo Formation, systematic petrographic and geochemical investigations were conducted for the outer shelf sections in the Yangtze block (see Chapter 3). Methane-derived authigenic calcite cements and nodules with extreme 13C-depletion were discovered and interpreted as the first empirical evidence of authigenic mineralization associated with the SE. In light of these novel observations, it is proposed that the globally distributed SE may be formed by widespread syndeposition of authigenic carbonates in a sulfate-methane transitional zone positioned at the sediment-water interface in response to a global seawater sulfate increase.
    [Show full text]
  • Towards Prediction of Saturated-Zone Pollutant Movement in Groundwaters in Fractured Permeable-Matrix Aquifers: the Case of the UK Permo-Triassic Sandstones
    Downloaded from http://sp.lyellcollection.org/ by guest on September 24, 2021 Towards prediction of saturated-zone pollutant movement in groundwaters in fractured permeable-matrix aquifers: the case of the UK Permo-Triassic sandstones JOHN H. TELLAM & RONALD D. BARKER Hydrogeology Research Group, Earth Sciences, School of Geography, Earth and Environmental Sciences, Birmingham University, Birmingham B15 2TT, UK (e-maik J.H. [email protected]. uk; R.D. Barker@bham. ac. uk) Abstract: The UK on-shore Permo-Triassic sandstones are fluvial and aeolian red beds showing a nested cyclic architecture on scales from millimetres to 100s of metres. They are typical of many continental sandstone sequences throughout the world. Groundwater flows through both matrix and fractures, with natural flow rates generally of less than 200 m year-1. At less than 30 m horizontal distances, below important minimum representative volumes for both matrix and fracture network permeability, breakthroughs are likely to be multimodal, especially close to wells, with proportionately large apparent dispersivities. 'Antifractures' - discontinuities with permeability much less than that of the host rock - may have a dominating effect. Where present, low-permeability matrix (e.g. mudstones) will significantly affect vertical flow, but will rarely prevent eventual breakthrough. Quan- titative prediction of breakthrough is associated with large uncertainty. At scales of 30 to a few 100s of metres, multimodal breakthroughs from a single source become less common, although very rapid fracture flow has been recorded. At distances of hundreds of metres to a few kilometres, there is evidence that breakthroughs are unimodal, and may be more immediately amenable to quantitative prediction, even in some cases for reacting solutes.
    [Show full text]
  • Soil Solution Chemistry, Profile Development, and Mineral
    AN ABSTRACT OF THE THESIS OF Joseph Reed Glasmann for the degree of Doctor of Philosophy in Soil Science presented on January 28, 1982 Title: Soil Solution Chemistry, Profile Development, and Mineral Authigenesis in Several Western Oregon Soils. Abstract approved: Redacted for Privacy Dr. Gerald H. Simonson Clay mineral genesis was studied in soils representative of several different geomorphic surfaces in western Oregon, ranging in age from Pliocene-early Pleistocene to late Pleistocene. Soil solution studies, clay mineralogy, and soil micromorphology were employed to provide evidence of clay mineral synthesis and interpret soil genesis. Soils at each study area were characterized by distinct differences in soil solution chemistry, clay mineralogy, plasmic fabric, and genetic history, although parent material compositions between sites were often similar. Soil solution studies suggested that clay mineral synthesis from solution does not occur in soils representing the oldest geomorphic surface. The oxic soil properties at this location were developed during a prior weathering cycle and the soils are at agenetic endpoint in the present environment. Soil solutions from Ultisols on remnants of Pleistocenesurfaces in the Oregon Coast Range were in equilibrium with respect tokaolinite in the solum, but stable with respect to Mg-montmorillonitein the zone characterizing active bedrock weathering. Micromorphological, clay mineralogical, and chemical evidence suggestedthat alteration of Mg- chlorite in sedimentary rocks leads tosmectite genesis in the Cr horizon of the Ultisols, followed by conversion of smectite to halloysite and chloritic intergrade in the solum. Alteration of basalt in these soils also leads to the formation of smectite, which is unstable with respect to halloysite in well-drained microenvironments withinsoil profiles.
    [Show full text]
  • Comparison of Authigenic Minerals in Sandstones and Interbedded Mudstones, Siltstones and Shales, East Berlin Formation, Hartford Basin, Usa
    Bull. Chem. Soc. Ethiop. 2007 , 21(1), 39-61. ISSN 1011-3924 Printed in Ethiopia 2007 Chemical Society of Ethiopia COMPARISON OF AUTHIGENIC MINERALS IN SANDSTONES AND INTERBEDDED MUDSTONES, SILTSTONES AND SHALES, EAST BERLIN FORMATION, HARTFORD BASIN, USA Wolela Ahmed Department of Petroleum Operations, Ministry of Mines, P.O. Box 486, Addis Ababa, Ethiopia (Received November 28, 2005; June 19, 2006) ABSTRACT. The East Berlin formation consists mainly of alternating sequences of fluviatile, lacustrine and playa sediments. Diagenetic sequences reconstruction revealed the same range of authigenic minerals in the studied sandstones and the interbedded fine-grained sediments (mudstones and siltstones). This indicates that the diagenetic processes that took place in the sandy facies also took place in fine-grained sediments. Mechanically infiltrated clays, grain- coating clay/hematite, quartz and feldspar overgrowths, carbonate cements and pore-filling and pore-lining clay minerals that precipitated in the sandy facies also precipitated in the fine-grained sediments. The abundance of authigenic minerals in decreasing order include: sandstone > siltstone > mudstone > shale. Except minor amounts of authigenic illite-smectite and illite, the shaly facies dominated by detrital clay, carbonate, quartz and feldspars framework grains. Authigenic minerals such as quartz, albite and K-feldspar are absent in the shaly facies, possibly related to early destruction of porosity. The lacustrine sandstones, siltstones and mudstones followed marine diagenetic trend, whereas playa and fluviatile sandstones, siltstones and mudstones followed red bed diagenetic trend. Mechanically compacted mudstones, siltstones and shales expelled large volume of mineralized pore water, which might migrated into the sandstone- rich section. Part of the ions for the precipitation of quartz overgrowths and carbonate cements in the sandy facies possibly contributed from the interbedded siltstones, mudstones and shales facies.
    [Show full text]